Rotating electrical machine

ABSTRACT

A rotating electric machine, e.g. hydrogenerator, includes a rotor, including a rotor laminate stack extending in a machine axis direction and having a rotor winding which forms a winding head at each of the ends of the rotor laminate stack. The winding head is fastened to a winding head rim, which is arranged concentrically within the winding head and adjoins the rotor laminate stack in the axial direction, to intercept centrifugal forces by bolts passing radially through the winding head, and a fastening designed to safely absorb axial expansions of the winding head. Simple and secure fastening is achieved by the bolts being fastened to the winding head rim in each case on a T-shaped hammer profile, which extends axially and is mounted, axially movable, in a T-shaped groove in the winding head rim, additional couplers are provided that transmit axial expansions of the winding head onto the hammer profile.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefit under 35 U.S.C. 119 to German PatentApplication No. 10 2011 109 952.6, filed Aug. 11, 2011, the entirecontents of which are incorporated by reference herein as if fully setforth.

FIELD OF THE INVENTION

The present invention relates to the field of electric machines. Itrelates to a rotating electric machine, in particular a hydrogenerator.

BACKGROUND

The invention relates to a rotor of an electric machine, in particular ahydrogenerator, as is used in pumped storage plants, for example, with arotor body which is constructed from laminated metal sheets and is heldtogether by axial clamping bolts. Axial winding slots are arranged overthe outer circumference of the rotor body, with a rotor winding beinginserted into said winding slots and held therein counter to the actionof centrifugal forces. The winding bars emerging axially from the rotorbody and forming a winding head are protected from the effects ofcentrifugal forces by special supporting means.

In such machines, the winding head on the rotor is subject to extrememechanical and thermal loads. The support of the winding head withrespect to centrifugal forces can in this case take place by means ofbanding consisting of prestressed steel wire in combination with a solidintegral steel ring. The complex fitting aids, the transportationdimensions and the weight limitation of the rotor result in limitations,however. For rotors of hydraulic prime movers with large dimensions, itneeds to be possible to perform the assembly directly at an installationposition in the power station. Furthermore, large solid steel ringsimpair the flow through the winding head and therefore cooling of saidwinding head.

Document DE 195 13 457 discloses arranging press fingers on the endlaminations of the rotor body and providing a supporting ring comprisingat least two rings which are spaced apart from one another in the axialdirection and which are supported at their inner circumference on thehub, the rings being clamped together, in that section of the rotor bodywhich is close to the axis, together with the press fingers with thefirst tie bolt which passes axially through the rotor body. In thesection which is further from the axis, second tie bolts are provided,which pass axially through only said rings and clamp the rings togetheraxially. Finally, third tie bolts are provided which pass radiallythrough the winding head and act at least on the outer circumference ofthe outermost, when viewed axially, ring.

A large number of axially running, mutually aligned, half-closed slotsare provided distributed in the circumferential direction over the outercircumference of all of the rings, into which in each case one straightedge provided with radially running threaded bores is inserted, withsaid third tie bolts being screwed into said threaded bores. Thisprovides secure radial support which can be produced easily.

However, in this known arrangement, the axial thermal expansion of thewinding on heating can result in the winding pressing onto the windinghead bolts (the third bolts) and said bolts experiencing undesired andintolerable bending.

The document WO 2010/115481 proposes, for avoiding these problems, adynamoelectric machine with a rotor body, a ring-shaped winding head,which is arranged axially next to the rotor body and coaxially withrespect thereto, and a supporting ring, which is arranged radiallywithin the winding head and coaxially with respect thereto, the windinghead and supporting ring being connected to the rotor body inrotationally fixed fashion and the winding head and the supporting ringbeing clamped to one another in the radial direction by tension rods,which are passed through radial bores in the winding heads and in thesupporting ring. The tension rods in this case act with their radiallyinner ends on the supporting ring and with their radially outer ends onthe bearing blocks, which bear against the winding head. The clearwidths of radial bores in the supporting body have an excess dimensionin comparison with the diameters of the tension rods, and the bearingarrangement of the radially inner ends of the tension rods on thesupporting ring and the radially outer ends of the tension rods on thewinding head enables a limited tilting movement of the tension rodstowards the radial direction. This is achieved in particular in that atleast some of the ends of the tension rods are mounted by means ofbearing blocks, which have a spherical bearing surface.

However, one disadvantage with this solution is that all of the tensionrods need to be prepared individually for a tilting movement, whichresults in considerable design and fitting complexity.

SUMMARY

The present disclosure is directed to a rotating electric machineincluding a rotor, which includes a rotor laminate stack extending in amachine axis direction and having a rotor winding. The rotor windingforms a winding head at each end of the rotor laminate stack. Thewinding head is fastened to a winding head rim, which is arrangedconcentrically within the winding head and adjoins the rotor laminatestack in an axial direction, in order to intercept centrifugal forces bymeans of bolts passing radially through the winding head, and afastening being designed to safely absorb axial expansions of thewinding head. The bolts are fastened to the winding head rim in eachcase on a T-shaped hammer profile which extends in the axial directionand is mounted in an axially movable fashion in an associated axialT-shaped groove in the winding head rim. Additional couplers are alsoprovided that transmit the axial expansions of the winding head onto theT-shaped hammer profile.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in more detail below with reference toexemplary embodiments in connection with the drawings, in which:

FIG. 1 shows a perspective side view of a detail of a rotor of arotating electric machine in accordance with one exemplary embodiment ofthe invention; and

FIGS. 2 a-2 b show, in two different views, one from above (FIG. 2 a)and one from the side (FIG. 2 b), the coupling between the winding headand fastening in accordance with one exemplary embodiment of theinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Introduction to theEmbodiments

One object of the invention is therefore to provide a rotating electricmachine of the type mentioned at the outset which avoids thedisadvantages of the known machines as regards the protection of thewinding heads against centrifugal forces and is characterized byneutralization, which is effective and simple in design terms, of thethermal expansion of the winding heads.

The object is achieved by the totality of features in claim 1.

The invention is based on a rotating electric machine, in particular ahydrogenerator, comprising a rotor, which comprises a rotor laminatestack extending in the direction of a machine axis and having a rotorwinding, the rotor winding forming a winding head at each of the ends ofthe rotor laminate stack, said winding head being fastened to a windinghead rim, which is arranged concentrically within the winding head andadjoins the rotor laminate stack in the axial direction, in order tointercept centrifugal forces by means of bolts passing radially throughthe winding head, and the fastening being designed to safely absorbaxial expansions of the winding head.

The bolts are fastened to the winding head rim in each case on aT-shaped hammer profile, which extends in the axial direction and ismounted in axially movable fashion in an associated axial T-shapedgroove in the winding head rim, additional couplers that transmit theaxial expansions of the winding head onto the T-shaped hammer profilebeing provided.

In one configuration of the machine according to the invention, theadditional couplers comprise a fixed mechanical coupling between thewinding head and the T-shaped hammer profile.

In particular, the T-shaped hammer profile engages with a radial part,which is bent back radially outwards, behind the winding head and isconnected to the winding head on the radial part by means of an axialconnector.

In another configuration of the machine according to the invention, thebolts are in the form of screw bolts and are screwed into the T-shapedhammer profile.

In a further configuration of the machine according to the invention, aplurality of bolts with the same radial alignment are arranged onebehind the other in the axial direction, and that all of the bolts withthe same radial alignment are fastened on a common T-shaped hammerprofile or screwed into a common T-shaped hammer profile.

In particular, all of the bolts with the same radial alignment act onthe winding head from the outside via a common holding element.

DETAILED DESCRIPTION

FIG. 1 shows a perspective side view of a detail of a rotor of arotating electric machine 10 in accordance with one exemplary embodimentof the invention. The rotor 11, of which only a section can be seen,extends along a machine axis 20 and comprises a rotor body or a rotorlaminate stack 12, with a winding head rim 13 adjoining said rotorlaminate stack at the illustrated end.

Axial winding slots which accommodate the rotor winding (notillustrated) are arranged on the outer circumference of the rotorlaminate stack 12. The exposed winding bars (15 a, b in FIGS. 2 a,b)emerging from the rotor laminate stack 12 form a winding head (15 inFIGS. 2 a,b), which needs to be supported with respect to thecentrifugal forces occurring during operation of the machine.

For this purpose, radially oriented bolts 18 are provided in the regionof the winding head 15, said bolts reaching through the winding head 15and being fastened to the winding head rim 13. In order to enable freeaxial expansion of the winding head 15 and fastening thereof, the entirewinding head fastening needs to compensate for the thermal expansions ofthe winding. In the proposed solution, this is achieved by virtue of thefact that the winding head fastening can move in the axial direction.For each axial series of bolts 18 with the same radial alignment, ineach case one common axially extending T-shaped hammer profile 17 isprovided, on which the bolts 18 for the winding head 15 are fastened.The T-shaped hammer profile 17 is provided with correspondinglyspaced-apart threaded holes for this purpose, with the bolts 18 in theform of threaded bolts being screwed with their inner ends into saidthreaded holes. The T-shaped hammer profiles 17 are guided axially inaxially oriented, matching T-shaped slots 16 in the winding head rim 13.The bolts 18 are supported with their head on a common, axiallyextending holding element 24 on the outer side, and said holding elementexerts pressure on the winding head 15.

Owing to the described design of the winding head 15 and its fasteningon the winding head rim 13, firstly the centrifugal forces occurringduring operation on the winding head 15 are intercepted and introducedinto the winding head rim 13 and secondly the thermal expansion of thewinding does not result in the buildup of any shear forces at the bolts18, because said bolts can collectively with the entire fasteningrelative to the winding head rim 13 in the axial movement direction 19illustrated in FIG. 1 by virtue of the T-shaped hammer profile 17sliding in the T-shaped slot 16 in the axial direction.

In order to transmit the thermal expansion of the winding directly ontothe T-shaped hammer profiles 17, in accordance with the inventionadditional coupling means are provided between the winding head 15 andthe T-shaped hammer profiles 17. The coupling of the T-shaped hammerprofile 17 to the winding or the winding head 15 is realized via anintermediate piece, the axial connector 23, between a radial part 22,which is bent back radially outwards, at the outer end of the T-shapedhammer profile 17 and the winding head 15. The axial connector 23 isintroduced without play between the solder lugs 21 of the winding head15 and the radial part 22 or the shoulder of the T-shaped hammer profile17. The axial connector 23 which is bent back and engages beneath thewinding head 15 is held in position in the radial direction in turn by a(the outer) winding head bolt 18, as shown in FIG. 2 b.

As soon as the winding expands thermally and the solder lugs 21 moveaxially correspondingly, the T-shaped hammer profile 17 is also pushedalong parallel to this. The winding head bolts 18 are in this way onlytensioned and do not experience any bending.

LIST OF REFERENCE SYMBOLS

10 rotating electric machine (in particular hydrogenerator)

11 rotor

12 rotor laminate stack

13 winding head rim

14 winding slot

15 winding head

15 a, b winding bar

16 T-shaped slot

17 T-shaped hammer profile

18 bolts (winding head)

19 movement direction

20 machine axis

21 solder lug

22 radial part

23 axial connector

24 holding element

1. A rotating electric machine (10) comprising a rotor (11), whichcomprises a rotor laminate stack (12) extending in a machine axis (20)direction and having a rotor winding (15 a, b), the rotor winding (15 a,b) forming a winding head (15) at each end of the rotor laminate stack(12), said winding head being fastened to a winding head rim (13), whichis arranged concentrically within the winding head (15) and adjoins therotor laminate stack (12) in an axial direction, in order to interceptcentrifugal forces by means of bolts (18) passing radially through thewinding head (15), and a fastening (16, 17, 18, 21) being designed tosafely absorb axial expansions of the winding head (15), the bolts (18)are fastened to the winding head rim (13) in each case on a T-shapedhammer profile (17), which extends in the axial direction and is mountedin an axially movable fashion in an associated axial T-shaped groove inthe winding head rim (13), additional couplers (22, 23) are alsoprovided that transmit the axial expansions of the winding head (15)onto the T-shaped hammer profile (17).
 2. The rotating electric machineas claimed in claim 1, wherein the additional couplers (22, 23) comprisea fixed mechanical coupling (22, 23) between the winding head (15) andthe T-shaped hammer profile (17).
 3. The rotating electric machine asclaimed in claim 2, wherein the T-shaped hammer profile (17) engageswith a radial part (22), which is bent back radially outwards, behindthe winding head (15) and is connected to the winding head (15) on theradial part (22) by means of an axial connector (23).
 4. The rotatingelectric machine as claimed in claim 1, wherein the bolts (18) are inthe form of screw bolts and are screwed into the T-shaped hammer profile(17).
 5. The rotating electric machine as claimed in claim 1, wherein aplurality of bolts (18) with the same radial alignment are arranged onebehind another in the axial direction, and all of the bolts (18) with asame radial alignment are fastened on a common T-shaped hammer profile(17) or screwed into a common T-shaped hammer profile (17).
 6. Therotating electric machine as claimed in claim 5, wherein all of thebolts (18) with the same radial alignment act on the winding head (15)from the outside via a common holding element (24).
 7. The rotatingelectric machine as claimed in claim 1, wherein the machine is ahydrogenerator.